package com.wangjw.leetcode;

/**
 * Created by wangjw on 18/7/4.
 */
public class LeetCode303_2 {

    private int[] sum; // sum[i]存储前i个元素的和, sum[0] = 0

    public LeetCode303_2(int[] nums) {
        sum = new int[nums.length + 1];
        sum[0] = 0;
        for (int i = 1; i < sum.length; i++) {
            sum[i] = sum[i - 1] + nums[i - 1];
        }
    }

    public int sumRange(int i, int j) {
        return sum[j + 1] - sum[i];
    }
}
